Comparative Study of the Three-Body Abrasive Wear Behavior of Natural Human Teeth and Plastic Teeth

A modified reciprocating friction and wear tester was performed to evaluate the friction and wear behavior of natural teeth and artificial plastic teeth sliding against a TC4 titanium alloy ball in the presence of food slurry as the third body. The wear scars of the natural and plastic teeth were observed using a laser co-focus scanning microscope. It was found that the natural teeth and the plastic teeth all showed different tribological behaviors in two- and three-body abrasion. Namely, the natural teeth had remarkably smaller friction coefficient and wear scar depth under three-body abrasive wear condition than under two-body abrasive wear condition, which was attributed to the lubricity of the food slurry as the third body and its action to de-concentrate the stress. However, the plastic teeth had more severe wear under the three-body abrasive wear condition than under two-body abrasive wear condition, which was attributed to the low hardness and poor mechanical strength of the plastic teeth. Moreover, the natural teeth were characterized by scratch and accompanied delamination under the three-body abrasive wear condition, while the natural teeth were dominated by ploughing and delamination under the three-body abrasive wear condition. This conformed to their different abrasive wear-resistance as well.